International Association
for Cryptologic Research

Adaptively secure multiparty computation first studied by Canetti, Feige, Goldreich, and Naor in 1996, is a fundamental notion in cryptography. Adaptive security is particulary hard to achieve in settings where arbitrary number of parties can be corrupted and honest parties are not trusted to properly erase their internal state. We still do not know how to realize constant round protocols for this task against even if we were to restrict ourselves to semi-honest adversaries and to the simpler two-party setting. Specifically the round complexity of known protocols grows with the depth of the circuit the parties are trying to compute.

In this work, using indistinguishability obfuscation, we construct a UC-secure two-round adaptively secure multiparty computation protocol.